Plz answer fast as my exam is tomorrow .

when going up: max ht it reaches:h

v2-u2=2gh

2x10xh=20x20

h=20 m

v=u-gt

t=2s....to reach the highest height.

while cominbg down: it has to cover=105+20=125m

u=o

so:  s=ut+1/2  at^2

125=5t^2

t=5sec

so total time=5+2=7 s